Tight junctions, which are located on the apical side of epithelial cells, are key components of epithelial intercellular junctional complexes. Tight junctions seal the space between neighboring cells and act as a semipermeable barrier, preventing the paracellular transport of ions and molecules. The tight junctions are calcium-dependent as their disassembly can be triggered by the depletion of calcium ions, and the subsequent addition of calcium promotes the formation of tight junctions and the restoration of their barrier function. This reversible process, known as the calcium switch, is often used to study tight junction dynamics. This chapter describes the calcium switch protocol for disrupting and reestablishing tight junctions using MDCK cells as an in vitro model. It also provides protocols for evaluating tight junction formation and integrity using the noninvasive, quantitative transepithelial electrical resistance (TEER) assay.